Device-to-device communication (D2D communication) is a communication form in which a signal is directly transmitted between terminal devices, unlike a communication form in which a signal passes through a base station in cellular communication. Therefore, in the D2D communication, new use forms of terminal devices unlike the existing cellular communication are expected to appear. For example, various applications such as information sharing by data communication between near terminal devices or a group of near terminal devices, information distribution from installed terminal devices, and autonomous communication between devices called Machine to Machine (M2M) can be considered.
With regard to the significant increase in data traffic with the recent increase of smartphones, the D2D communication can also be considered to be utilized in off-loading of data. In recent years, for example, demands for transmission and reception of streaming data of moving images have rapidly increased. However, since moving images generally have large data amounts, the moving images have a problem in that they consume many resources in a Radio Access Network (RAN). Accordingly, when terminal devices are in a state suitable for the D2D communication such as a case in which a distance between terminal devices is small, resource consumption and process loads in the RAN can be suppressed by off-loading moving image data in the D2D communication. Thus, the D2D communication is useful for both communication providers and users. Therefore, at present, the D2D communication is recognized and noticed as one of the important technical areas necessary for Long Term Evolution (LTE) of the 3rd Generation Partnership Project (3GPP) standardization commission as well.
In the related art, as disclosed in the following patent literature, communication schemes such as Bluetooth (registered trademark) and WiFi (registered trademark) have been adopted in the D2D communication and combinations of such communication schemes and communication schemes of cellular communication such as Wideband Code Division Multiple Access (WCDMA) (registered trademark) and LTE have been combined as an example.